1. Field of the Invention
The present invention relates to a liquid ejection head for ejecting liquid from an ejection opening and a printing apparatus.
2. Description of the Related Art
The printing speed and image quality of an inkjet printer become higher, and accordingly, the density of a liquid ejection head becomes higher. Accordingly, members included in the liquid ejection head become smaller and thinner. Therefore, a substrate and a flow path forming member which are major members included in the liquid ejection head tend to deform because of stress caused by adhesion or the like.
In a case where a flow path forming member deforms, an ejection opening deforms which is formed in the flow path forming member to eject liquid, and it becomes difficult to accurately land liquid at a targeted position on a printing medium. Further, there may occur a problem that the substrate and the flow path forming member peel off.
As a means for suppressing such deformation of the substrate and the flow path forming member, there is a method disclosed in Japanese Patent Laid-open No. 2007-331245. In the method disclosed in Japanese Patent Laid-open No. 2007-331245, at least one slit, groove, or dent is provided on an upper surface of the flow path forming member to relieve stress caused by the volume shrinkage of the flow path forming member, thus suppressing peeling at an interface with the substrate.
As an adhesive for joining the substrate and the flow path forming member, a thermosetting adhesive is used from the viewpoint of ink resistance. The adhesive is heated and cured and the shrinkage stress of the substrate which is generated in a case where the temperature of the substrate is returned to a normal temperature is applied in a direction to pull the flow path forming member. In the method disclosed in Japanese Patent Laid-open No. 2007-331245, grooves are provided on the upper surface of the flow path forming member to prevent deformation and peeling from being caused by stress generated by the volume shrinkage of the flow path forming member.